Carl luckow



ATENT rricE.

CARL LUCKOW, OF OOLOGNE-DEUTZ, GERMANY.

PROCESS OF PRODUCING ACID CHROMATE OF LEAD.

SPECIFICATION forming part of Letters Patent No. 627,266, dated June 20,1899.

Application filed December 31, 1897. Serial No. 665,212. (No specimens.)

To all whom it ntay concern.-

Be it known that I, CARL LUoKow, a subject of the King of Prussia,German Emperor,

residing at Oologne-Deutz, Germany, have invented certain new and usefulImprovements in Processes of Producing Acid Chromate of Lead by Means ofElectrolysis, of which the following is a specification.

The invention has been patented in England, No. 14,801, dated August 6,1895.

The object of this invention is to produce acid chromate of lead bymeans of electrolysis.

It consists, essentially, in the use of a salt of chloric acid withsodium, potassium, or ammonium in mixture with a salt of chromic acidwith sodium, potassium, or ammonium in aqueous solution. The mixtureshould be about eighty per cent. of one of the salts named above ofchloric acid and about twenty per cent. of one of the salts named aboveof chromic acid, and the aqueous solution should contain from 0.3 tothree per cent. of the mixture, the quantities of salt always calculatedfree from water. This solution serves as electrolyte. The electrodes areof lead. Under the influence of the electric current the lead of theanode is dissolved by the chloric acid of the one salt, forming chlorateof lead, which dissolves and is directly precipitated by the chromicacid of the other salt as acid chromate of lead. At the same time wateris decomposed, the oxygen of which enters into the chromate of lead,while the hydrogen escapes. The following chemical formulae will explainthe process somewhat further:

2OlO Na OrO Na Chlorate of sodium chromate of sodium in 4.1 1 0 OrO,H

is then precipitated by the chromic acid as OrO,,Pb 2Gl0 H. chromate oflead and chloric acid regenerated. The reactions go,"therefore, onaccording to the chemical equations:

The chromic acid and the water thus consumed must be continuously addedafresh to the electrolyte. By the use of such two salts in about suchproportions and such weak aqueous solutions the acid chromate of leadformed does not adhere to the anodes, which keep bright. The processgoes on continuously with the same electrolyte, as the chloric acid isnot decomposed by the electric current and as the chromic acid and waterconsumed in the process are always added as they are consumed. Theelectrolyte being kept acid by a surplus of chromic acid, acid chromateof lead is obtained.

Example: A diluted solution one and onehalf per cent. strong of amixture of eighty parts, by weight, of chlorate of sodium with twentyparts, by Weight, of chromate of sodium forms the electrolyte. The anodeconsists of soft lead and the cathode of hard lead, an alloy of lead andantimony containing fivetenths per cent. of thelatter. The electrolyteis faintly acid. The tension of the currentis 1.5 volts. The intensityof the same is fifty amperes. The density of the same is 0.5 ainperesper square decimeter of anode-surface. The electrolyte has to be keptfaintly acid during the electrolysis, and water and chromic acid havecontinuously to be added.

What I claim is- The herein-described process of producing acid chromateof lead by means of electrolysis the continuous addition of Water andchromic by using in connection with an anode of lead acid. 10 an aqueoussolution as electrolyte containing In Witness whereof I have hereuntoset my from 0.3 to three per cent. of the sodium, pohand in presence oftwo Witnesses.

tassium or ammonium salts of chloric acid in CARL LUGKOVV.

mixture with the sodium, potassium or am- Witnesses: monium salts ofchromic acid passing the cur- WILLIAM H. MADDEN, rent and maintainingthe bath constant by l OTTO STREOKER.

